a) Field of the Invention
The invention is directed to a vacuum valve comprising a valve housing with an interior space which forms a vacuum area of the vacuum valve and with first and second valve openings which have parallel longitudinal axes and which are surrounded by first and second valve seats, a closure member comprising first and second closure plates, a transverse drive for adjusting the closure member in an actuation direction transverse to the longitudinal axes of the valve openings between an open position, in which the closure plates free the valve openings, and an intermediate position in which the closure plates cover the valve openings but are raised from the valve seat, a first longitudinal drive for adjusting the closure member between the intermediate position and a first closed position in which the first closure plate is pressed against the first valve seat, and a second longitudinal drive for adjusting the closure member between the intermediate position and a second closed position in which the second closure plate is pressed against the second valve seat.
b) Description of the Related Art
A vacuum valve of the type mentioned above is known from U.S. Pat. No. 6,390,448 B1. A closure member of this vacuum valve has first and second closure plates which can be pressed alternately against first and second valve seats surrounding first and second valve openings. By means of a transverse drive unit, the closure member is adjustable transverse to the longitudinal axes of the valve openings between an open position and an intermediate position in which the closure plates cover the valve openings but are raised from the valve seats. The transverse drive unit is arranged at a swiveling part which is swivelable around a pin. By means of a driving element, the swiveling part can be swiveled around its swiveling axis in order to press the first closure plate against the first valve seat. The driving element and the swiveling pin for the swiveling part are arranged at another swiveling part which is swivelable around another swiveling axis by means of another driving element. By swiveling the additional swiveling part around the additional swiveling axis, the second closure plate can be pressed against the second valve seat. This design is relatively complicated. Also, this vacuum valve is designed for relatively small valve openings.
U.S. Pat. No. 6,776,394 B2 discloses a vacuum valve in which a valve disk is arranged at a swiveling arm. The swiveling arm is arranged at a shaft which is swivelable around an axis of rotation and which is displaceable in direction of the axis of rotation. The shaft is guided relative to the valve housing by means of a slotted guide. A pin which acts in connection with the slotted guide, is screwed into an internal thread of the shaft and is rotatable by means of a driving element serves to displace the shaft in direction of the axis of rotation and to rotate the shaft around the axis of rotation. Further, driving elements in the form of piston-cylinder units which cooperate with tappet-like actuating elements guided into the vacuum area are provided in the valve housing. The closure plate can be pressed against the valve seat with additional force by these driving elements in the closed position of the closure plate.
In the vacuum valve known from US 2004/0079915 A1, the closure member has a carrying part at which a closure plate is arranged, this closure plate being displaceable by means of piston-cylinder units. In the position of the closure member in which it covers the valve opening, the closure plate can be pressed against the valve seat surrounding the valve opening by means of the piston-cylinder units. Also preferably provided is a supporting plate which is displaceable relative to the carrying part by means of piston-cylinder units. In the closed position of the closure plate, the supporting plate is pressed against an opposite wall of the valve housing in an area surrounding another valve opening. Elastomer rings are arranged at the closure plate and at the supporting plate for cooperating with the wall of the valve housing.
FR 2 283 375 discloses a nongeneric vacuum valve in which only one valve opening can be closed by the closure member. Contact pressing cylinders are used as a longitudinal drive to press the closure member against the valve seat of the valve opening, this closure member being guided in the lateral guide grooves. Additional contact pressing cylinders acting in the opposite direction are needed to open the closure member so as to move the closure member back in the guide grooves sufficiently to allow the valve opening to be fully freed subsequently by means of a transverse drive unit.